Downhole seal apparatus and method

ABSTRACT

Disclosed herein is a tubular seal apparatus. The seal apparatus includes, a first tubular positioned coaxially with a second tubular having an annular space therebetween, a frustoconical portion at the first tubular having a first end and a second end, such that a radial dimension of the annular space is larger at the first end than at the second end and a tubular seal positioned within the annular space. The seal apparatus further includes an urging member in operable communication with the tubular seal, the urging member is axially movable relative to the frustoconical portion such that movement of the urging member toward the second end of the frustoconical portion urges the tubular seal into sealing engagement with the frustoconical portion and causes diametrical deformation of the tubular seal to thereby sealingly engage with the second tubular.

BACKGROUND OF THE INVENTION

In the hydrocarbon recovery industry it is often necessary to sealtubulars to one another in a downhole environment. Packers, for example,typically employ seals with packing elements that when actuated seal onetubular to another tubular. These seals can be complicated assembliesthat require significant actuation forces to set as well as to maintaintheir seal integrity. Additionally, the reliability and durability ofthese seals in the high pressure, high temperature and causticenvironments encountered downhole can be questionable. As such, areliable downhole tubular to tubular seal that is easy to set would bewelcomed in the art.

BRIEF DESCRIPTION OF THE INVENTION

Disclosed herein is a tubular seal apparatus. The seal apparatusincludes, a first tubular positioned coaxially with a second tubularhaving an annular space therebetween, a frustoconical portion at thefirst tubular having a first end and a second end, such that a radialdimension of the annular space is larger at the first end than at thesecond end and a tubular seal positioned within the annular space. Theseal apparatus further includes an urging member in operablecommunication with the tubular seal, the urging member is axiallymovable relative to the fruistoconical portion such that movement of theurging member toward the second end of the frustoconical portion urgesthe tubular seal into sealing engagement with the fristoconical portionand causes diametrical deformation of the tubular seal to therebysealingly engage with the second tubular.

Further disclosed herein is a method of sealing downhole tubulars. Themethod includes, positioning a tubular seal in an annular space betweena first tubular and a second tubular, axially urging the tubular sealagainst a frustoconical portion of the first tubular thereby sealinglyengaging the tubular seal with the fruistoconical portion anddiametrically deforming the tubular seal thereby sealingly engaging thetubular seal with the second tubular.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 depicts a partial cross sectional view of a tubular sealapparatus disclosed herein in a seal open configuration;

FIG. 2 depicts a partial cross sectional view of the tubular sealapparatus of FIG. 1 in a seal closed configuration;

FIG. 3 depicts a partial cross sectional view of the tubular sealapparatus of FIG. 1 in a seal closed configuration; and

FIG. 4 depicts a partial cross sectional view of an alternate tubularseal apparatus disclosed herein.

DETAILED DESCRIPTION OF THE INVENTION

A detailed description of several embodiments of the disclosed apparatusand method are presented herein by way of exemplification and notlimitation with reference to the Figures.

Referring to FIG. 1 a partial cross sectional view of an embodiment ofthe tubular seal apparatus 10 disclosed herein is illustrated. Thetubular seal apparatus 10 includes a first tubular 14, a tubular seal 22and an urging member 26 positioned within a second tubular 18. The firsttubular 14, the second tubular 18 and the tubular seal 22 may all bemade of a rigid material such as metal, for example, which providesexcellent resistance to the high pressure, high temperature and causticenvironments often found downhole. The first tubular 14 is coaxial withthe second tubular 18 such that an annular space 30 is formedtherebetween. The first tubular 14 has a frustoconical portion 34 with afirst end 38 and a second end 42. A diameter of the frustoconicalportion 34 at the first end 38 is smaller than a diameter of the secondend 42 such that a radial dimension of the annular space 30 is greaterat the first end 38 than at the second end 42. The tubular seal 22 ispositioned, in the annular space 30, such that it is coaxial with thetubulars 14, 18. The tubular seal 22 is sealable with both the firsttubular 14 and the second tubular 18 to reliably prevent flow throughthe annular space 30. Such a tubular seal apparatus 10 is usable forsealing tubulars in downhole packers, for example. Details and operationof the tubular seal apparatus 10 will be described below.

The tubular seal 22 is made of a rigid material such as metal, forexample, and has an inner frustoconical surface 46 that has a divergentangle 50 that substantially matches a divergent angle 54 of an outerfrustoconical surface 58 of the frustoconical portion 34. In a seal openconfiguration 62, as shown in FIG. 1, the surfaces 46 and 58 contacteach other with the tubular seal 22 positioned at the first end 38 andaxially spaced a distance from the second end 42. In the seal openconfiguration 62 an outer radial surface 66 of the tubular seal 22 isdiametrically smaller than an inner radial surface 70 of the secondtubular 18 thereby providing an annular flow space 74 therebetween.

The tubular seal 22 is moved axially by the urging member 26. The urgingmember 26 has a collar portion 78 and a collet portion 82. The collarportion 78 is engagable with and axially movable by any one of a varietyof actuators (not shown) that are known in the industry for axialactuation of common downhole devices. These therefore do not requiredetailed description herein. The collar portion 78 is fixedly engagablewith the first tubular 14 by a lock ring disclosed herein as ratchetdevice 86 that permits axial movement of the urging member 26 in anaxial direction according to arrow 90 while not permitting axialmovement in a direction opposite to the arrow 90 relative to the firsttubular 14. The collet portion 82 includes longitudinal slots (notshown) formed therein to allow the collet portion 82 to expanddiametrically outwardly as it urges the tubular seal 22 along thefrustoconical portion 34. The collet portion 82 is fixedly attached tothe tubular seal 22 by latch detail 94 such that axial movement of theurging member 26 causes a similar axial movement of the tubular seal 22.The attachment of the tubular seal 22 to the urging member 26 by thelatch detail 94 also locks in any additional axial movement of the sealdue to applied pressure from the right side.

Axial actuation of the urging member 26 in the direction of the arrow 90urges the tubular seal 22 into sealing engagement with the frustoconicalportion 34. Continued motion of the urging member 26 and the tubularseal 22 causes the tubular seal 22 to deform diametrically outwardly, inthis embodiment. This diametrical expansion of the tubular seal 22includes the diametrical expansion of the outer radial surface 66 untilthe outer radial surface 66 comes into contact with the inner radialsurface 70 of the second tubular 18. Sealing engagement results betweenthe tubular seal 22 and the second tubular 18 when adequate contactpressure between the outer radial surface 66 and the inner radialsurface 70 is achieved. Adjustments in the force required to axiallymove the urging member 26 to achieve the necessary contact pressures canbe adjusted in the design phase of the tubular seal apparatus 10. Morespecifically, lower urging forces can be attained by using smallerdivergent angles 50, 54, for example, as compared to larger divergentangles 50, 54. Alternate embodiments of the tubular seal apparatus couldhave the frustoconical portion on an inner radial surface of an outertubular, for example. In such an embodiment, a tubular seal would bedeformed diametrically inwardly due to axial movement of the tubularseal into engagement with the diametrically decreasing dimension of thefrustoconical portion. As such, the diametrical deformation of thetubular seal would cause the tubular seal to sealingly engage with anouter radial surface of an inner tubular.

A diametrically protruding bump 98, or step, at the second end 42 of thefrustoconical portion 34 is contactable by a leading edge 102 of thetubular seal 22 to prevent the tubular seal 22 from extruding through anannular gap 106 between the first tubular 14 and the second tubular 18beyond the frustoconical portion 34 in the direction of the arrow 90.The leading edge 102 may have a reversed angle formed thereon that mateswith a similar shaped reversed angle on the bump 98 to furtherdiscourage extrusion of the tubular seal 22 through the annular gap 106.

Referring to FIG. 2, the tubular seal apparatus 10 is illustrated in aseal closed configuration 110. The inner frustoconical surface 46 is insealing engagement with the outer frustoconical surface 58 and the outerradial surface 66 is in sealing engagement with the inner radial surface70. The leading edge 102 is in contact with the bump 98 therebypreventing the tubular seal 22 from extruding through the annular gap106. Maintaining the seal between the tubular seal 22 and the tubulars14, 18 upon release of a force urging the urging member 26 and thetubular seal 22 in the direction of the arrow 90 is facilitated bymaterial choice and the incorporation of one or more grooves in thetubular seal 22 as will be described below.

Referring to FIG. 3, the tubular seal apparatus 10 is illustrated in aseal closed configuration 112. As with most common ratchet devices 86,upon release of a force urging the urging member 26 in the direction ofthe arrow 90 there may be a small amount of reverse axial movement ofthe urging member 26 until the ratchet device 86 is fully engaged. Thissmall amount of reverse axial movement of the urging member 26 alsoallows for a similar reverse axial movement of the tubular seal 22. Sucha reverse axial movement of the tubular seal 22 is revealed by an axialgap 114 between the leading edge 102 and the bump 98. Such an axial gap114 could result in a potential leak-path between the surfaces 46 and58, or the surfaces 66 and 70, if the deformation of the tubular seal 22were completely plastic with no elastic component.

Incorporating one or more grooves 118 in the inner frustoconical surface46, or the outer radial surface 66, between non-grooved end portions120, can increase the elasticity of the tubular seal 22 as compared totubular seals 22 that do not include the grooves 118. This increase inelasticity is due to the creation of beams 122 that can flex over alength of the beam 122 thereby providing for a greater deflection beforeexceeding the elastic limit of the material. Thus, even aftersignificant plastic deformation, through the diametrical expansion ofthe tubular seal 22, the elastic deformation of the beam 122 will remainallowing for greater variations in the radial dimension between theinner radial surface 70 and the outer frustoconical surface 58 overwhich the tubular seal 22 can maintain sealing engagement. Thedimensions and quantity of the grooves 118 utilized can be optimized perapplication to provide the robustness desired at the sealing pressuresneeded.

Robustness of the sealing integrity between the tubular seal 22 and thetubulars 14, 18 can be increased even further through the incorporationof a filler material 126 in the grooves 118. The filler material 126 canadd to the robustness in two ways. First, by having elastomericproperties the filler material 126 can seal around imperfections in thesurfaces 46, 58, 66 and 70. And second, the filler material 126 canprevent sides 130 of the groove 118 from collapsing against one another.

Referring to FIG. 4, an alternate tubular seal apparatus 200, disclosedherein, is illustrated in a seal open configuration 204. The tubularseal apparatus 200 includes the first tubular 14, a tubular seal 210 andan urging member (not shown) that is similar to the urging member 26,positioned within the second tubular 18. The tubular seal 210 includes afirst tubular portion 214 and a second tubular portion 218. The tubularportions 214, and 218 are made of a rigid material such as metal, forexample. The first tubular portion 214 is fixedly attached to the secondtubular portion 218 by fixing means known in the industry such as bythreads 222, for example. Similar to the tubular seal apparatus 10 thefirst tubular portion 214 has a plurality of grooves 226 at an outerradial surface 230 and a plurality of grooves 226 formed at an innerradial surface 234 thereof. The grooves 226 are located such that thefirst tubular portion 214 resembles a pleated bellows, the significanceof which will be described below. The grooves 226 may be filled with afiller material 236 that is a material different than the material ofthe first tubular portion 214 and aids in sealing and in preventing thegrooves 226 from collapsing. In this embodiment, both of the radialsurfaces 230 and 234 have substantially constant radial dimensions suchthat each pleat 238 of the first tubular portion 214 is substantiallygeometrically similar to all of the other pleats 238.

The inner radial surface 234 of the first tubular portion 214 restsdiametrically flush against an outer radial surface 242 of the secondtubular portion 218. The outer radial surface 242 has a substantiallyconstant radial dimension while an inner frustoconical surface 246 ofthe second tubular portion 218 has a frustoconical shape withsubstantially a same angle of divergence as that of the frustoconicalportion 34 of the first tubular 14. As such, as the tubular seal 210 isurged up the frustoconical portion 34 the second tubular portion 218expands diametrically outwardly. The outer radial surface 242 alsoexpands diametrically outwardly causing the first tubular portion 214 toexpand diametrically outwardly as well. This outward diametricalexpansion continues until the outer radial surface 230 sealingly engageswith the inner radial surface 70 of the second tubular 18.

The seal of the annular gap 106 by the tubular seal 210 allows pressurein the annular gap 106 on a side of the tubular seal 210 (which is theuphole side in this figure) opposite a side of the tubular seal 210 onwhich the threads 222 are located, to build without leaking by thetubular seal 210. The tubular seal 210 is constructed such that as theuphole pressure increases the sealing pressure, between the firsttubular portion 214 and the two surfaces 70, 242 to which the firsttubular portion 214 is sealed, also increase. This is due, in part, to aresponse of the bellows geometry, of the first tubular portion 214, tothe pressure increase. The pressure increase acts against the firsttubular portion 214 in a direction to collapse the grooves 226 uponthemselves. In order for the grooves 226 to collapse, however, each side252 of each of the grooves 226 would need to move closer to one another.Moving the two sides 252 towards one another, however, causes the volumetherebetween to decrease that in turn creates an extruding force on thefiller material 236 positioned within each of the grooves 226. Thisextruding force on the filler material 236 increases the sealingpressure between the filler material 236 and the surfaces 70, 242.Additionally, the sides 252 of each groove 226 are substantiallystraight segments (in the cross sectional view) that are loaded incompression between the two surfaces 70, 242 as the uphole pressure actsto collapse the grooves 226. This action of wedging these sides 252between the surfaces 70, 252 causes the sealing pressure between thefirst tubular portion 214 and the surfaces 70, 252 to increase therebyimproving the seal integrity further. The second tubular portion alsoallows the seal to be pushed up the ramp without compressing thebellows.

While the invention has been described with reference to an exemplaryembodiment or embodiments, it will be understood by those skilled in theart that various changes may be made and equivalents may be substitutedfor elements thereof without departing from the scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe claims.

1. A tubular seal apparatus, comprising: a first tubular positionedcoaxially with a second tubular having an annular space therebetween; afrustoconical portion at the first tubular, the frustoconical portionhaving a first end and a second end, such that a radial dimension of theannular space is larger at the first end of the frustoconical portionthan a radial dimension of the annular space at the second end of thefrustoconical portion; a tubular seal positioned within the annularspace; and an urging member hi operable communication with the tubularseal, the urging member being axially movable relative to thefrustoconical portion such that movement of the urging member toward thesecond end of the frustoconical portion urges the tubular seal intosealing engagement with the frustoconical portion and causes diametricaldeformation of the tubular seal to thereby sealingly engage with thesecond tubular.
 2. The tubular seal apparatus of claim 1, wherein thefrustoconical portion is disposed at an outer radial surface of thefirst tubular.
 3. The tubular seal apparatus of claim 1, wherein thefrustoconical portion has a bump at the second end that prevents axialmovement of the tubular seal therebeyond.
 4. The tubular seal apparatusof claim 1, wherein the tubular seal has at least one circumferentialgroove therein.
 5. The tubular seal apparatus of claim 4, wherein theapplication of pressure on the seal causes walls of the circumferentialgroove to get closer together.
 6. The tubular seal apparatus of claim 4,wherein the at least one circumferential groove is at an outer radialsurface of the tubular seal.
 7. The tubular seal apparatus of claim 4,wherein the at least one circumferential groove comprises at least onecircumferential groove at an outside radial surface of the tubular sealand at least one circumferential groove at an inside radial surface ofthe tubular seal.
 8. The tubular seal apparatus of claim 4, wherein theat least one circumferential groove is filled with a material other thanthe material from which the tubular seal is made.
 9. The tubular sealapparatus of claim 4, wherein the at least one circumferential grooveprovides an increase in elastic deformation of the tubular seal ascompared to the tubular seal without the at least one circumferentialgroove.
 10. The tubular seal apparatus of claim 1, wherein the tubularseal is made of metal.
 11. The tubular seal apparatus of claim 1,wherein the urging member further comprises a collet portion, the colletportion being axially fixed to the tubular seal, the collet portionhaving longitudinal slots therein, the longitudinal slots allowingdiametrical deformation of the collet portion.
 12. The tubular sealapparatus of claim 1, wherein the urging member is axially fixable tothe first tubular with a lock ring.
 13. The tubular seal apparatus ofclaim 1, wherein the tubular seal has a frustoconical surface thatcontacts the frustoconical portion.
 14. The tubular seal apparatus ofclaim 13, wherein the frustoconical surface has substantially a sameangle of divergence as an angle of divergence of the frustoconicalportion.
 15. The tubular seal apparatus of claim 1, wherein the tubularseal is a packer seal.
 16. The tubular seal apparatus of claim 1,wherein the first tubular is positioned radially inwardly of the secondtubular.
 17. The tubular seal apparatus of claim 1, wherein the tubularseal is comprised of two tubular portions, a first tubular portionhaving at least one circumferential groove therein and a second tubularportion having an inner frustoconical surface with substantially a sameangle of divergence as an angle of divergence of the frustoconicalportion.
 18. The tubular seal apparatus of claim 17, wherein an outerradial surface of the second tubular portion has a substantiallyconstant radial dimension and an inner radial dimension of the firsttubular portion engages with the outer radial surface of the secondtubular portion.
 19. A method of sealing downhole tubulars, comprising:positioning a tubular seal hi an annular space between a first tubularand a second tubular, the second tubular being substantially coaxialwith the first tubular; axially urging the tubular seal against afrustoconical portion of the first tubular thereby sealingly engagingthe tubular seal with the frustoconical portion; and diametricallydeforming the tubular seal thereby sealingly engaging the tubular sealwith the second tubular.
 20. The method of sealing downhole tubulars ofclaim 19, wherein the diametrically deforming further includes expandingthe tubular seal diametrically outwardly.
 21. The method of sealingdownhole tubulars of claim 19, further comprising maintaining sealing ofthe tubular seal with the first tubular and the second tubular bypreventing axial movement of the tubular seal in a direction opposite toa direction of the axial urging.
 22. The method of sealing downholetubulars of claim 19, further comprising forming at least onecircumferential groove in the tubular seal thereby increasing a sealingpressure between the tubular seal and at least one of the frustoconicalportion and the second tubular.
 23. The method of sealing downholetubulars of claim 19 further comprising filling the at least onecircumferential groove thereby preventing collapse of the at least onecircumferential groove.
 24. The method of sealing downhole tubulars ofclaim 19 further comprising increasing a sealing pressure between thetubular seal and at least one of the first tubular and the secondtubular in response to an increase in pressure on an axial side of thetubular seal that is opposite to a side of the tubular seal from whichthe tubular seal is urged.